Electric motors, such as those typically used in hybrid electromechanical powertrains for automotive vehicles, have a stator surrounding a rotor that is rotatable relative to the stator. The stator is grounded to a stationary member, such as a transmission housing or casing. It is important that the relative positions of the stator and rotor remain substantially constant in order to preserve a precisely sized gap between the stator and rotor. This is of special difficulty in the case of a vehicle transmission or other powertrain component, because the electric motor may be subjected to extreme vibration and mechanical shock from the travel of the vehicle over bumps or other rough terrain. The stator is grounded to the transmission casing by any of a number of methods, such as bolting or slip-fitting. The stator must maintain its position relative to the casing, both axially and radially, when the casing and/or stator expand and contract due to thermal variations. Stators are steel, as they must generate an electromagnetic field when energized in order to move the rotor. Casings may be of a different, non-ferrous material, such as an aluminum alloy or plastic, with a greater coefficient of thermal expansion than steel.